http://elinux.org/index.php?title=Support_same_log_buffer_or_tracing_buffer_in_both_bootloader_and_kernel&feed=atom&action=history 2013-05-23T03:41:10Z Revision history for this page on the wiki MediaWiki 1.21alpha http://elinux.org/index.php?title=Support_same_log_buffer_or_tracing_buffer_in_both_bootloader_and_kernel&diff=129938&oldid=prev 2012-05-17T05:19:15Z

<p></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr style='vertical-align: top;'> <td colspan='2' style="background-color: white; color:black;">← Older revision</td> <td colspan='2' style="background-color: white; color:black;">Revision as of 05:19, 17 May 2012</td> </tr><tr><td colspan="2" class="diff-lineno">Line 36:</td> <td colspan="2" class="diff-lineno">Line 36:</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Comments ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Comments ==</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[Category:Project proposals 2012]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[Category:Project proposals 2012]]</div></td></tr> <!-- diff cache key elinux:diff:version:1.11a:oldid:129932:newid:129938 --> </table>

Hisaomunakata http://elinux.org/index.php?title=Support_same_log_buffer_or_tracing_buffer_in_both_bootloader_and_kernel&diff=129932&oldid=prev 2012-05-17T05:18:42Z

<p>Created page with &quot;; Summary: Support same log buffer or tracing buffer in both bootloader and kernel ; Proposer: Tim Bird - Sony Network Entertainment == Description == It would be nice to share ...&quot;</p> <p><b>New page</b></p><div>; Summary: Support same log buffer or tracing buffer in both bootloader and kernel<br /> ; Proposer: Tim Bird - Sony Network Entertainment<br /> <br /> == Description ==<br /> It would be nice to share log buffer or trace buffers between the bootloader and the kernel,<br /> so that either log messages or trace events (respectively) could be coalesced from both sources in a<br /> unified view.<br /> <br /> This work might be related to work involving using fixed memory locations for kernel<br /> buffers. This is done implicitly by Android's RAM-console feature, and by PRAMFS.<br /> Alternatively, if performance is not an issue, the kernel could copy messages<br /> from the bootloader log buffer into the kernel log buffer at startup.<br /> <br /> It appears that U-boot uses a log-buffer format similar to the Linux kernel.<br /> (See http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=blob;f=common/cmd_log.c<br /> <br /> Note that this is useful for on-box analysis (using 'dmesg' locally, and getting both<br /> bootloader and kernel messages). It is obvious that someone with a serial console<br /> can see both sets of text messages coalesced, and could use a tool like<br /> http://elinux.org/Grabserial to get timing information for the text messages.<br /> (Although, due to delays in setting up the kernel console device, the timings<br /> are inaccurate for a portion of the bootup.)<br /> <br /> Handling trace events in a coalesced fashion is a whole other issue.<br /> <br /> == Related work ==<br /> * In 2009 there was a proposal to add an &quot;alternative log buffer&quot; for printk messages<br /> ** See http://lwn.net/Articles/315943/<br /> * Does u-boot support any tracing code similar to ftrace?<br /> <br /> == Scope ==<br /> Unknown<br /> <br /> == Contractor Candidates ==<br /> No one so far.<br /> <br /> == Comments ==<br /> <br /> [[Category:Project proposals 2012]]</div>

Hisaomunakata